In a medium sauce pan, cook the flour in the butter for about 2 minutes on medium heat, do not brown the flour. Pour in water and half-and-half. Stir until the mixture thickens, then add 3/4 of the bag of cheese. Reserve the remainder for topping. Set aside the mixture to cool.
Shred potatoes and rinse well. Chop onion finely. Microwave the spinach in the package until it is mostly thawed but not hot. Place spinach in a clean towel and wring out as much liquid as possible. In a large bowl combine spinach, onion and potatoes. Add half of the cheese mixture. Stir to combine.
Place one chicken breast into a gallon size freezer bag, using a mallet pound the breast until it is about double in size. Using a sharp knife cut open the two sides of the bag but leave the bottom intact; remove breast. Lay flat on a cutting board for poultry, lightly salt and pepper both sides of breast. Repeat for the other three breasts.
Stuff each breast with 1/4 of spinach mix and roll up sealing both ends, and tucking the ends under the breast. Place each stuffed breast into a baking dish, spoon the remaining cheese mixture over each breast, cover with foil. Bake at 375 for 45 minutes. Remove from oven, remove foil, and top with Kraft Parmesan Cheese and remaining Swiss cheese. Bake for 15 to 20 minutes more, or until cheese is golden brown.